Some implantable medical devices (IMDs) monitor physiological parameters or signals of the patients within which they are implanted. Such implantable medical devices may detect episodes based on the monitoring. An IMD may store a variety of data regarding detected episodes, and a clinician may retrieve the episode data from the IMD for diagnosing the patient and/or confirming the accuracy of the detection of the episodes by the IMD. For example, implantable cardioverter-defibrillators (ICDs) may detect cardiac episodes, such as tachyarrhythmia episodes, based on monitoring cardiac electrogram signals and, in some cases, additional physiological signals or parameters. A clinician may review the data stored by the ICD for the episodes to confirm that accuracy of the diagnosis of tachyarrhythmia by the ICD.
As the memory capacity and diagnostic capabilities of IMDs, such as ICDs, increases, the amount of time required to adequately review the retrieved data to determine whether the detection of episodes and delivery of therapy by the device was appropriate also increases. Manual review of episodes may be challenging because of the number of patients a clinician follows, an increase in the total number of episodes to review and the significant level of expertise required. Additionally, the time available for clinicians with expertise to review each episode has been reduced. This may result in a reduction in the quality of management of those patients having implanted devices.
Automated algorithms for post-processing cardiac episodes previously detected by ICDs have been proposed to address these concerns. Such algorithms generally evaluate the cardiac electrogram and other data stored by an ICD for an episode to provide an independent classification of the episode. The post-processing classification may be compared to the classification made by the ICD to determine the accuracy of the classification by the ICD. Such algorithms may potentially suggest ICD parameter changes and/or changes to medical therapy, such as changes in medication, therapy delivery, use of ablation procedures, etc. One algorithm for automated algorithms for post-processing of cardiac episodes is disclosed in U.S. Pat. No. 7,894,883 to Gunderson et al., which is incorporated herein by reference in its entirety.